下面的特殊效果和轮廓有关的是？（）
A、查找边缘
B、龟纹
C、描摹轮廓
D、边缘检测
参考答案：A, C, D
This is quite a difficult problem and none of us could ____ a solution to it. [ ]
A. come about
B. come out
C. come up to
D. come up with
商法包括哪几部分？
